In recent decades and particularly in recent years, electronic technology, including communication technology, has revolutionized our everyday lives. Portable electronic devices such as mobile phones, tablet computers, PDAs, or the like, have permeated the lives of almost every person. Mobile communication and computing devices, especially, have become the means by which countless millions conduct their personal and professional interactions with the world. It has become almost impossible for many people to function without access to their electronic devices, thus the devices are carried by their users almost constantly.
Determining the location of people and tracking their routes in some resolution has become easier and is often used for a variety of purposes, such as navigation, child security, location based services and others.
When a person is carrying a mobile phone, determining the person's location may be done by one or more of some known methods such as but not limited to arrival time methods, determining radiating cells closest to the mobile phone by considering the received signal strength, RF triangulation and trilateration methods, Global Positioning Systems (GPS) or the like.
In general, these methods are based on providing two or more transmitters and measuring signals that enable to determine a location of an object relatively to the transmitters. By measuring the intensity of the received signal and using models of wave propagation in a medium, the distance from a transmitter may be evaluated. In alternative embodiments, the distance between an object and a transmitting or receiving station which is at a known location may be evaluated by measuring the arrival time of a predetermined signal transmitted by the transmitter to the object, or the other way around. Repeating the process for a multiplicity of transmitters and crossing the results enable to provide an estimated location of the object in space. In alternative methods, the difference in arrival time of signals transmitted by two transmitters may be measured and used for evaluating the location.
These methods may be used indoors or outdoors. However, in indoor locations a serious limitation is for example the reduced signal to noise ratio caused in particular by increased multipath phenomena, which may be caused by reflection, diffraction or other effects of a close environment.
Additional location methods may be based upon identifying a pattern of parameters received at a location, such as the pattern of the signal intensity, from a particular network, the general noise pattern, or the like. A table indicating the pattern may be constructed for each location, and when it is required to identify the location of an object, the pattern received by the object may be compared to entries in the table, such that the entry containing the closest pattern is indicative of the device location.
Yet additional location methods may be based on dead reckoning, for example inertial navigation systems (INS), hybridization, or a fusion of any two or more of the methods.
However, these techniques may require special equipment or expensive infrastructure. Some of these methods may also suffer additional drawbacks. For example, GPS-based method are limited to outdoor locations, in which a navigation device or a navigation system within a mobile phone, for example, has line of sight to satellites and can receive direct satellite signals.
Determining the accurate indoor location of a person can be used for a multiplicity of purposes, including but not limited to: providing navigation instructions to an indoor location, presenting information, suggesting promotions or coupons, activating systems for example illuminating certain areas when a person is approaching, displaying commercials on a billboard, locating children, or others.